Michael PietersDept. of Diagnostic Radiology Bloemfontein

CONGENITAL HEART DISEASE WITH LEFT

TO RIGHT SHUNT

Classification of congenital heart lesions

Factors that influence lesion presentation

Imaging chain sequence

Left to right Shunt lesions Anatomy Physiology Imaging

OVERVIEW

Shunt lesionsRight heart lesionsLeft heart lesionsAbnormal origin of the great arteries

CLASSIFICATION OF CONGENITAL CARDIAC LESIONS

Age of childSeverity of the lesion

Example – VSD R to L shunt at birth L to R shunt with CCF as age increases

The anatomy of the lesion remains constantRadiographic features and clinical findings change

with time

Classic radiographic features of certain lesions – rarely seen

FACTORS THAT INFLUENCE LESION PRESENTATION

The imaging sequence varies with Age Clinical presentation Type of lesion

EchocardiographyChest RadiographyCTMRIAngiography

IMAGING CHAIN SEQUENCE

ASD

VSD

PDA

Ductus Arteriosus Aneurysm

Aortico-Pulmonary Window

CONGENITAL CARDIAC LEFT TO RIGHT SHUNT LESIONS

Cardiomegaly on CXRAsses pulmonary vascularity - ? IncreasedRead history - ? Acyanotic patient

Ddx: ASD AVSD VSD PDA Aortico-pulmonary window

CARDIOMEGALY

10% of all CHD

Incidence - twice as common in females

Secundum defects – likely genetic cause Holt Oram Familial ASD

ASD

3 Primary typesRelationship to the fossa ovalis

Secundum defects (80%) Region of fossa ovalis

Ostium Primum defects (10%) Caudal to the fossa ovalis

Sinus Venosus defects (10%) Posterior to the fossa ovalis

ASD ANATOMY

Not true ASD’sDefect in the septum which separates the

sinus venosus portion of the RA from the right pulmonary veins and systemic veins

Most often found in the wall between the Posterior inferior border of SVC and RA

Commonly assosciated with anomalous connection of Right upper, middle or lower pulmonary veins draining to

the RA or SVC

ASD – SINUS VENOSUS DEFECTS

Much less commonly - defect is found in the wall between the Inferior RA at its junction with the IVC

Assosciated with anomalous connection of Right middle or lower pulmonary veins draining to the RA or SVC

ASD – SINUS VENOSUS DEFECTS

Rare spectrum of lesions

Partial or complete absence of wall between Coronary sinus and LA Associated with a left SVC draining to the coronary sinus

Blood shunts from the LA to the RA via “unroofed” coronary sinus

ASD – CORONARY SINUS SEPTAL DEFECTS

Foramen Ovale Located between septum secundum and primum

Normally patent prenatally Allows O2 rich blood from ductus venosus -> reach LA

Sealed after birth Increased LA pressure vs RA

Probe patency 25% of adults Functionally closed Right to left shunt possible - Valsalva

ASD – PATENT FORAMEN OVALE

Atrial septum completely absent

Common in visceral heterotaxy syndromes

ASD – COMMON ATRIUM

Left to right shunt volume determined by ASD size Left heart compliance Pulmonary vascular resistance

Large defects show increased size of RA RV Pulmonary artery

Right to left shunt will occur when Pulmonary vascular resistance > Systemic vascular

resistance

ASD - PHYSIOLOGY

Detected 1-2 yr of age

May present earlier @ 6-8 weeks with murmur

Older children with large ASD Fatigue and dyspnoea Split second heart sound – no variation with respiration Diastolic flow murmur

Adults – flow related pulmonary arterial hypertension

ASD – CLINICAL PRESENTATON

Modality of choice for Dx Localising Size Shunt direction and severity (Colour Doppler)

Right ventricular qualitative function Septal bowing (Rt to Lt) Points to volume overload

ASD IMAGING - ECHOCARDIOGRAPHY

Right ventricular pressure Assessed by evaluating the degree of: Tricuspid regurgitation Septal systolic position (systolic septal flattening –

increased RV pressure)

PFO Dx – flap valve or Saline injection to right heart + Valsalva Rt to Lt shunt on Valsalva TEE

ASD IMAGING - ECHOCARDIOGRAPHY

Neonate Normal cardiac size Normal pulmonary flow

Later infancy and childhood Mild cardiomegaly Triangular cardiac silhouette Left atrium normal

distinguishes uncomplicated ASD from other L->R lesions) Main pulmonary artery enlarged Eisenmenger syndrome findings

Seen in pulmonary hypertension Large central pulmonary arteries Peripheral pulmonary artery tapering

ASD IMAGING – CHEST RADIOGRAPHY

Mild to moderate cardiomegaly

Increased pulmonary vascularity

No left atrial dilatation

ASD IMAGING – CHEST RADIOGRAPHY

Angiography Asses haemodynamic consequences of ASD or Used if transcatheter closure is planned

MRI Adjunct to echo >90% sensitive and specific for ASD localization and

detection Useful in pt with poor acoustic windows Can lead to ASD being misdiagnosed

atrial septum is thin on BW images – rather use MRI cine GE and steady state free precession cine – shows turbulent

jet over ASDCine phase contrast sequences

Show direction and amount of shunting

ASD – IMAGING

PFO can be demonstated by injecting Gadolinium into the right heart + Valsalva

ASD haemodynamic evaluation

Demonstrates Eisenmenger syndrome physiology Contrast seen crossing the atrial septum from the RA to the

LA

ASD – MRI DYNAMIC PERFUSION STUDY

2-5% of all CHD

40% of Down’s syndrome patients have CHD

40% of Down’s pt with CHD have AVSD

Associated with visceral heterotaxia / asplenia and polysplenia syndromes

Ellis van Creveld syndrome

AVSD

Lesions associated with AVSD

PDA (10%) Tetralogy of Fallot (6%) Transposition of the great arteries Double outlet RV Aortic coarctation

AVSD

Abnormal development of the endocardial cushions

Mild form - partial AVSD: Crescent shaped defect in the inferior portion of the atrial

septum adjacent to the AV – valves Cleft mitral valve Separate mitral and tricuspid valve orifices

AVSD - ANATOMY

Complete form: Single AV-valve Ostium primum ASD just superior to the plane of the AV –

valve Large VSD beneath the plane of the AV - valve Cleft in the anterior leaflet of the mitral valve Cleft in septal leaflet of tricuspid valve The common AV-valve has 5 leaflets Shortened left ventricle inlet Left ventricle papillary muscle defects

abnormally close to each other or only one papillary muscle

Unbalanced AVSD Relative hypoplasia of one of the ventricles

AVSD - ANATOMY

Complete AVSD Left to right shunt - related to size of defect and pulmonary

vascular resistanceShunting may be interatrial or interventricularCleft Mitral Valve leads to mitral regurgitation and

CCFPulmonary hypertension develops (more common in

Down’s pts)

AVSD - PHYSIOLOGY

Infants with complete AVSD Tachypnoea, tachycardia CCF sx when pulmonary resistance starts to fall

Signs and symptoms vary according to the degree of shunting

Partial AVSD Infants usually asymptomatic Can present earlier if severe mitral incompetence

AVSD PRESENTATION

Echocardiography

Accurately demonstrates AVSD components Ostium primum defect Inlet portion of the ventricle Abnormal valve leaflet morphology Papillary muscle architechture Shunt level and flow direction Ventricular function and size

Evaluate for outflow tract obstruction Pulmonary and systemic venous anatomy (must be

documented because of frequency of associated heterotaxy abnormalities)

AVSD - IMAGING

Chest Radiography

Moderate to marked cardiomegaly RV and RA enlargement (more in complete AVSD) Increased pulmonary vascularity Left atrial enlargement – if associated mitral incompetence Lung infiltrates (increased pulmonary blood flow associated

with recurrent LRTI) Lung hyperinflation – seen with large left to right shunts

due to increased blood volume with increased overall lung volume as well as increased airway resistance from enlarged arteries and veins

AVSD - IMAGING

Chest Radiography Cardiomegaly Pulmonary plethora

AVSD - IMAGING

Cross sectional imaging Not needed in initial Dx Used to confirm Dx and evaluate the size and morphology of the atria, leaflets,

ventricles and great vessels Evaluate ventricular function

Cine phase contrast MRI Assessment of shunt fraction (Qp/Qs) Valvular function

AVSD - IMAGING

Angiocardiography Rarely necessary for Dx Used if Dx is unclear or haemodynamic information is

needed

Long axis ventriculogram Goose neck deformity of left ventricular outflow tract Anterior superiorly positioned aortic valve Elongated and narrowed LV outflow tract

AVSD - IMAGING

20% of all CHD2/1000 Live brithsVSD + complex CHD account for > 50% of CHDMost common lesion in trisomy 13,18 and 21 Incidence slightly higher in females Incidence varies on age of evaluation

Most small VSDs close spontaneously

VSD

Isolated or

as part of complex CHD Tetralogy of Fallot Truncus arteriosus ASD Coarctation of the aorta Tricuspid atresia Transposition of the great arteries Double outlet RV

VSD

4 Components of the ventricular septum Inlet septum Muscular septum Outlet septum Membranous septum

VSD involves one or more component

VSD - ANATOMY

Inlet septum Contains AV valves and their attachments Formed from endocardial cushions AVSD defect location

Muscular septum Trabeculated portion of RV (viewed from RV) From tricuspid valve leaflets to RV apex and crista

supraventricularis Location of single or multiple muscular defects

Outlet septum Extends from the crista supraventricularis to pulmonary valve

(viewed from RV)Membranous septum

Inferior to the right and non-coronary cusps of the aortic valve 80% of VSDs involve this area

VSD - ANATOMY

Physiologic eff ect determined by VSD size Rt and Lt heart compiance Pulmonary vascular resistance

Small defects High flow resistance

Large defects Low flow resistance High blood flow in the pulmonary vasculature Leads to pulmonary vascular obstructive disease

VSD - PHYSIOLOGY

Symptoms dictated by VSD size Degree of Left to Right shunt

Typical signs in > 1 month of age PSM as pulmonary resistance falls No murmur in large VSD Loud split 2nd heart sound

Significant shunt Failure to thrive Dyspnoea CCF Irreversable pulmonary vascular obstructive disease Shunt reversal

VSD - SYMPTOMS

Echocardiography Method of choice Used to asses the location, number and size of VSDs Shunt assessment Colour Doppler is useful to identify muscular VSDs RV + Pulmonary artery pressures measured Rt + Lt heart volumes are measured Tricuspid and Aortic valves

Assessed for possible tethering of the valve tissue into the defect borders

TEE used if poor acoustic windows

VSD - IMAGING

Chest Radiography Findings depend on VSD size Small VSD – may have normal CXR Moderate to large VSD

Cardiomegaly with LA, LV, RV enlargement Enlarged pulmonary arteries Increased pulmonary blood flow

CCF frequent in infants + large defects Older children – pulmonary hypertension likely

Large central pulmonary arteries Pruned peripheral pulmonary arterial branches

VSD - IMAGING

Echocardiography usually suffi cientMuscular VSDs sometimes detected on routine CT

Chest

MRI 90% accuracy in VSD detection Larger defects seen with

Spin Echo or Double inversion recovery techniques

Smaller defects seen with GE or Steady state free precession images

VSD – CROSS SECTIONAL IMAGING

MRI Shunt evaluation

Cine phase contrast measurements in aorta and pulmonary artery

Rt + Lt Ventricular stroke volume comparison

Quantative assessment Rt and Lt ventricular function Rt and Lt ventricular volumes Ejection fractions

Evaluation for extracardiac vascular anomalies

VSD – CROSS SECTIONAL IMAGING

Angiocardiography

Used to Assess pulmonary vascular resistance Quantify intracardiac shunting Evaluate for ventricular septal defect anatomy Evaluate the coronary arteries Evaluate for associated valvular and vascular anomalies

Angiocardiography used if echocardiographic evaluation was insuffi cient or if transcatheter VSD closure is planned

VSD - IMAGING

5-10% of CHD1/1600 live birthsTwice as common in females20-30% of prems have PDA

Often associated with VSD Aortic coarctation Aortic stenosis Mitral regurgitation

PDA

Persistence of embryologic 6 th aortic arch6 th Aortic arch connects Lt pulmonary artery with

descending aortaPDA may be on the right with a Rt arch

PDA - ANATOMY

Ductus Arteriosus / Aorta angle Acute angle seen in isolated PDA with pulmonary atresia

Ductal dependant pulmonary flow

Obtuse angle seen in Non-ductal dependant pulmonary flow

PDA - ANATOMY

PG keep the duct patent during foetal life At birth blood [O2] rises and [PG] lowers

Functional ductal constriction Complete closure @ 2 months Ligamentum arteriosum remains (may calcify)

In Premature infants closure is delayed due to Less sensitive ductal tissue to [O2] Respiratory distress – hypoxia -> increased [PG]

In full term infants Rubella Asphyxia Genetic and environmental causes

PDA –PROSTAGLANDINS AND O2

Amount of Lt to Rt shunt dictated by Ductal length and diameter Degree of pulmonary hypertension

Untreated PDA leads to Pulmonary vascular obstructive disease

Prem with no significant lung disease Systolic high frequency murmur CCF (large shunt)

Prem with significant lung disease PDA prevalence > 80% Almost inaudable murmer Dx with echocardiography

PDA - PHYSIOLOGY

Term infant with small PDA Usually asymptomatic Murmur present

Infant with moderate to large PDA Continuous machinary like murmur FTT Poor feeding CCF Irritability

PDA - PHYSIOLOGY

Echocardiography Standard imaging technique PDA size and diameter L->R Shunt fraction Degree of pulmonary hypertension Can identify complicating factors – ductal aneurysm or

calcification

Chest Radiography Premature infants

Pulmonary oedema Cardiomegaly +- Associated lung disease

PDA IMAGING

Chest Radiography Term infants

CXR may be normal

Term infants with significant shunting Cardiomegaly Increased pulmonary blood flow

Consider PDA in a prem infant with Increasing granularity of lung fields Increasing heart size on serial imaging

PDA IMAGING

Chest Radiography

Prominent ascending aorta and arch Helps differentiate ASD and VSD from PDA ASD and VSD have a normal aortic arch

Ductus bump Prominence of the descending aorta

PDA - IMAGING

Cross sectional Imaging

Reserved for complicated cases to define anatomy

CT / MRI – ductal size and length

Cine phase contrast sequences Can quantify the amount of flow through the PDA

PDA - IMAGING

Angiocardiography

Reserved for cases where significant pulmonary hypertension is suspected

Assess Pulmonary vascular resistance Ductal morphology if transcath closure planned

PDA - IMAGING

1.5 – 8.8% of full term infants

Usually Dx pre-natally or after birth in asymptomatic patients

Possible association with connective tissue disorders Ehlers-Danlos syndrome

ANEURYSM OF THE DUCTUS ARTERIOSUS (DAA)

Saccular or fusiform dilation of the PDA

Etiology unknown ? Intrinsic weakness of wall of the duct ? Delayed closure of aortic side of duct with exposure to

systemic pressures

DAA - ANATOMY

Chest Radiography

Ductal bump in area of main pulmonary artery and aortic arch

Echocardiography Most oft modality used for Dx

MRI/CT or Angiography Rarely used to confirm the Dx

DAA - IMAGING

Rare – 0.2% CHD30-50% associated with other abnormalities

VSD ASD PDA Tetralogy of Fallot Interrupted aortic arch Aortic coarctation Subaortic stenosis Anomalous coronary arteries – pulmonary trunk origin

AORTICO-PULMONARY WINDOW

Incomplete division of the primitive common arterial trunk

Two distinct semilunar valvesLarge oval communication between ascending aorta

and pulmonary trunk above the aortic valve

AORTICO-PULMONARY WINDOW -ANATOMY

Mori type I Involves the proximal medial wall of the ascending aorta

Mori type II Involves the distal posterior wall of the ascending aorta

Mori type III Involves the medial and posterior walls of the ascending

aorta

AORTICO-PULMONARY WINDOW –MORI CLASSIFICATION

Large high pressure Lt to Rt shunt

Presents in 1st weeks of life

CCF commonly seen

Systolic ejection murmur may be heard

Diastolic murmur – associated pulmonary insuffi ciency

Bounding pulses frequently encountered

AORTICO-PULMONARY WINDOW - PHYSIOLOGY

Echocardiography Method of choice For evaluation of defect anatomy

Relationship to the aortic and pulmonary valves To define coronary anatomy Pulmonary pressure and ventricular function Other defects

Chest Radiography Mimics PDA on CXR Cardiomegaly LA + LV enlargement Increased pulmonary blood flow Prominent ascending aorta and pulmonary artery

AORTICO-PULMONARY WINDOW - IMAGING

Cross sectional imaging MRI and CT can depict APW anatomy Used as adjunct to echo Shunt volume quantification Ventricular function evaluation

Angiocardiography Confirm Dx if echo questioned Used if pulmonary pressures are needed to be determined Critical to differentiate from truncus arteriosus (APW has

two distinct semilunar valves)

AORTICO-PULMONARY WINDOW - IMAGING

Echocardiography Mainstay

MRI / CT Complicated cases Also yields good physiological information

CXR Useful for screening

Angiography Complicated lesions Usually used where catheter angio intervention is planned

SUMMARY

Caff ey’s Pediatric Diagnostic Imaging 11 th ed – SlovisClassic Imaging Signs of Congenital

Cardiovascular Abnormalities – Ferguson et al - September 2007RadioGraphics, 27, 1323-1334.

http://www.yale.edu/imaging

Thank you

RESOURCES